Plate dampening means



, J 25 H. A. PRITCHARD PLATE DAMPENING MEANS 3 Sheets-Sheet 1 Filed March 27, 1952 INVENTOR.

A r roe/ways June 1957 H. A. PRITCHARD PLATE DAMPENING MEANS 3 Sheets-Sheet 2 Filed March 27, 1952 aczs'ouace, i

INVEN TOR. flow/mo A Pwrcwmo Arroezvsys June 25, 1957 H. A. PRITCHARD PLATE DAMPENING MEANS 5 Sheets-Sheet 5 Filed March 27, 1952 INVENTOR. flaw/m 4 k/TCl/ARD flrramvsys ZWAAQ Unite States Patent PLATE DAMPENIN G MEANS Howard A. Pritchard, Hiram, Ohio, assignor to Seybold Company, Cleveland, Ohio, a corporation of Delaware Application March 27, 1952, Serial No. 278,772

22 Claims. (Cl. 101-147) This invention relates to improvements in plate dampening means, that is to say apparatus for maintaining inkrepellent the non-printing areasof lithographic and life surfaces, such as are utilized in lithographic, collotype, aquatone or other similar printing processes wherein dampening of a planographic printing surface is required.

The invention will be described herein as applied to lithographic printing, and it has particular utility therein, but it is to be understood that Wherever the context permits reference to lithographic printing is intended to include similar kinds of printing wherein the printing surface is substantially planographic incharacter.

One of the objects of the invention is the provision of an improved method and means for applying dampening material to a lithographic surface.

Another object is the provision of a method and means of the character described wherein electrical force is employed to convey finely divided dampening material from a source to a lithographic surface.

Another object is the provision of an improved means for producing fog, mist or vapor for application to a lithographic surface.

A further object is the provision of means for controlling the amount and distribution of the dampening material in accordance with varying conditions encountered in printing.

Another object is the provision of apparatus of the character stated which is stable in operation, that is apparatus in which there is a minimum of variation in operating characteristics from the start of and throughout a prolonged period of use.

Another object is the provision of apparatus for applying moisture to a rotating cylindrical surface in which the escape of moisture to surrounding objects is maintained at "a minimum.

A further object is the provision of means for controlling the quantity of moisture applied to selected areas transversely of the plate cylinder. j

Still another object is the provision of means for causing only the smaller particles of moisture in a moving fog to reach the field of force of the electrode for application to the plate surface.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which i Fig. 1 is an elevational view, partly broken away, of apparatus constructed in accordance with the invention, the view looking toward the back of the apparatus.

Fig. 2 is a fragmental plan view showing one end of the apparatus. v

Fig. 3 is a vertical sectional view taken substantially on the line 3-3 of Fig. 1.

Fig. 4 isan end view partly in section and partly broken away and looking in the direction of arrow 4, Fig.2, and Fig. 5 is a detail sectional view taken substantially on the line 55 of Fig. 4. e r

In the drawings a fragment of the plate cylinder of'a rotary ofiset printing machine formed of metal is shown at 10. It is to be understood that the cylinder is mounted for rota-tion in suitable bearings provided in the frame It is further to be understood that inkof the machine. ing mechanism is provided comprising form rollers a fragment of one of which is shown at 11. Preferably, and as herein shown, the inking mechanism is disposed above the plate cylinder. The planographic plate, which may be either metallic or non-metallic, is indicated at 9.

Side members of the press frame are indicated at 12.

To this frame are bolted dampener frame members 13,. in which are formed pillows for the reception of the ends of a pipe or hollow shaft 14, which is normally clamped against rotation by caps 15. One end of pipe 14 is closed by a threaded plug 16, while in the other end there is a connection for attachment to a conductor 17 leading to a source of air under pressure. A pan for holding a supply of liquid, which may be water or water with certain chemicals added, is shown at V 18 extending across the frame of the press and supported therefrom by means of brackets 19. The remaining parts of the apparatus are carried exclusively by pipe 14 which extends crosswise of the press parallel to cylinder 10.

Pipe 14 carries a series of collars 20 secured on the pipe by setscrews 21. Each collar carries'a bracket 22 which supports a housing designated generally by the numeral 25, which is secured to bracket 22 by screws 26. The housings 25 which are arranged side by side and closely adjacent each other are sufficient in number'to make their combined width at least equal to the length of the body portion of plate cylinder 10.

Each housing 25 comprises a metallic top wall 27 and metallic side walls 28. The backwall 29 is conveniently constructed of transparent material, such as clear plastic, and it is preferably removable, being held in place by removable straps 30 which are fastened by screws 31 to bars 32 carried by the side walls 28. The bars 32 have flanges or ledges against which the forward surfaces of the back walls 29 bear.

The forward wall of each housing consists of an extension ofthe metal top 27 which is curved downwardly and rearwardly at 35 to form a narrow throat 36 between it and the cylinder 10. This forward w-all comprises also a rearwardly and downwardly extending portion 37 and an approximately semicylindri-cal portion 33 terminating in a forwardly projecting lip 39. The wall portions 35, 37, 38 and 39 will be referred to hereinafter as a shell of conducting material, preferably metal, indicated generally by the reference numeral 40. The shell is electrically connected with cylinder 10, for example through the framework of the machine, so that the shell and the cylinder are at substantially the same potential; Such potential is preferably that of ground, but'in any case is low relative to the-potential of wire 5% referred to 14 and held against movement thereon by a setscrew 43.

These plates have edges which are arcuate and extend into the cylinder reliefs 44 at the ends thereof. By this means there is formed a chamber 45 extending thelength ofthe working surface of the cylinder and closed at both ends but open at the bottom where there is necessarily a small elongatedopening- 46,;between theforward-rim of pan 18 and the cylinder, as 'well as a somewhat wider opening between lip 39 and the cylinder. 47 is a deflector mounted on the pan and extending downwardly below the liquid level therein- On the inner side of each end plate 41 there is a flange 105 which also extends into the cylinder relief 44 and serves to catch moisture escaping from the end housings and carry it down into the pan 18. This feature of the invention is rather import-ant because such moisture might otherwise collect in drops or globules and fall onto the plate, causing damage to the printing. 7

A straight wire electrode 50 for high voitage direct current is mounted within the chamber 45, preferably so as to be centered within the semicylindrical portion 38 of the shell. For this purpose there is provided a slab 51 of insulating material which is secured to a collar 52 surrounding pipe 14 and fixed thereon by a setscrew 53. One end of the wire is attached to a pin 54 carried in the slab 51. Pin 54 has a head 56 against which a spring 57 bears, tending to force pin 54 toward the left to put wire 50 under tension. The head 56 is prevented from too great movement by coming against the heads of screws 58 threaded into the slab 51. A removable cover 59 of insulating material having a recess 60 is provided to fit over the pin 54 and screws 58 to prevent contact of the press operator with the latter highly charged elements. Cover 59 is pivotally supported on a pin 61 threaded into slab 51 and is held against the latter by a compression spring 62 between the head of pin 61 and the bottom of a counterbore 63 in cover 59.

At its opposite end wire 50 is secured to a metal connector 64 carried in a thick slab 65 of insulating material which is secured to a collar 66 surrounding pipe 14 and fastened thereto by a setscrew 67. Connector 64 is threaded to a rod 68 having a hole 69 to receive a jack plug 70 secured to the end of a high potential cable 71. The plug 78 and wire 71 are carried in two insulating pieces 72, 73 threaded together at 74 and adapted to fit into openings in slab 65 to form a removable plug connection, in a well known manner. Wire 71- leads to a source of high voltage direct current electricity indicated at 75 in Fig. 2.

The voltage supplied will depend upon operating conditions and the dimensions of the apparatus. In the embodiment shown the radius of the semicylindrical portion 38 of shell 40 and the distance of wire 50 from plate cylinder are both of the order of one inch. Under such conditions voltages in the range of twelve thousand to twenty thousand volts may be used. Such voltage may be either plus or minus, but a plus value is preferred. The high voltage direct current supplied to the wire electrode 50 is preferably substantially continuous, although a pulsating current with at least the major portion of the wave on one side of the zero line will function satisfactorily.

Wire electrode 50 is surrounded between the endmos't housings and the insulating slabs 51 and 65 by metal tubes 76 of approximately the same radius as that of the semicylindrical portion 38 of shell 49. These tubes are mounted in round holes of the proper size formed in the metal plates 41 to which they are secured as by soldering or brazing. At their outer ends they abut against the insulating slabs 51 and 65 respectively. The spaces within these tubes therefore constitute cylindrical extensions of the chamber 45.

The housings 25 and the dampening liquid in pan 18 are so arranged that the liquid forms the bottom of each isecui'ed to the rear wall 29 of each housing 25 by screws 85 is a bracket 86 which supports a liquid and air spray nozzle 87 held firmly in the bracket by clamp ing screw 88. The nozzle has a siphon tube 89 extending downwardly into the pan 18 with its intake end below the normal level of liquid therein. The nozzle itself is directed through a hole 90 in wall 29 into the interior of the housing. Nozzle 87 is connected to the supply of air under pressure in pipe 14 by means of a nipple 91, coupling 92, adjusting valve 93, coupling 94 and hose 95.- Nozzle 87 also has the usual adjusting screw 96 for controlling the amount of liquid in the jet issuing from the nozzle.

Within housing 25, directly in line with the jet issuing from nozzle87, 'an air jet 97 is arranged issuing from a small hole in a pipe 98, plugged at its end, supported in a small bracket 99 secured to the top wall 27 of housing 25. Pipe 98 is connected by a hose 100 to coupling 92, so that air at substantially the same pressure may issue from pipe 98 and nozzle 87. The two jets oppose each other and intermingle, with the result that the force of the liquid containing jet is largely overcome and the particles of liquid remain in suspension in the air instead of being thrown with force against the rear surface of the shell 40.

While in the illustrated case the discharge from one of the opposed nozzles is exclusively air and that from the other nozzle is air and liquid, it should be understood that variations within the scope of the invetnion may be employed, as for'example opposed nozzles both of which discharge air and water, or opposed nozzles one of which discharges liquid exclusively and the other air exclusively.

As the moisture particles are generated by nozzle 87 and strike against the air jet from pipe 98, many of the particles remain suspended in the air in housing 25,

being held confined between the shell 40, rear wall 29 and end walls 28, except as they can escape through passage 83 and gap 84 toward the cylinder 10. As a cloud or fog of air and dampening fluid is built up by the continuous operation of the two nozzles, this fog is forced out through the gap 84 after which it enters the electrical field in chamber surrounding wire 50. Whatever particles of moisture are deposited on the in- Q ternal surfaces of the housing 25 flow down along its internal walls and drop back into the pain 18. The particles of moisture in the fog which thus enter the chamber 45 and come into the field of force on the forward side of electrode 50 become chargedand move under the influence of the said field onto the surface of the plate on cylinder 10. Those particles which escape from said field of force to the field of force rearward of the electrode are impelled by the latter field toward and collected upon the forward surface of shell 40. The moisture accumulating on the forward surface of the shell flows down to the lowest point thereof and drops through small holes 101 in the shell back into the pan. The shape of the shell is important since it is essential to avoid drops of liquid falling directly onto the surface of the plate, as that would spoil the printing.

The metal tubes 76 projecting from the endmost housings prevent moisture from depositing upon the surfaces of the insulating slabs 51 and 65, that is to say any mois ture escaping from the endmost housings is attracted to the inner walls of these grounded tubes and deposited there instead of upon the insulating slabs. If on the other hand the insulating slabs 51 and 65 were juxtaposed directly against the outer side walls of the endmost hous ings moisture collecting on the insulating slabs would sooner or later cause arcing from the electrode to the grounded housing.

Rotation of the cylinder 10 in the direction indicated in Fig. 3 tends to cause upward travel of the fog which enters thechamber 45. The greater part of this fog will pass in front of the electrode, and the particles therein will b'e'charged as they move upwardly between the cylinder and the electrode. They will thus be attracted toward the grounded cylinder. Those which are not previously deposited either upon the cylinder or upon the shell 40 will be directed toward the cylinder by the walls 37 and 35 of the shell into the narrow throat 36 where the shell and the cylinder are so close together that substantially all remaining particles are deposited here on the shell or the cylinder and none escape.

It will therefore be apparent that by the practice of the invention a fog of air and finely divided moisture particles is formed at a point remote from the electrode, that this fog has no directive force from the nozzles by which it is generated because of their opposed relation and the consequent dissipation of their force, that the fog thus generated is conducted into the field of force of the electrode at low velocity, the larger particles of moisture finding their way back into the pan during this movement of the fog, that the finer particles which travel into the field of force are charged and deposited by electric force onto the printing plate carriedby the plate cylinder or onto the metal shell behind the electrode, and that the shape of the shell provides a narrow throat between. it and the plate cylinder on the downstream side of the electrode, so that any charged particles not previously deposited on the plate or shell are quite certainly deposited on one or the other as they tend to pass through this throat under the influence of skin friction from the rotating cylinder.

In case the planographic plate is not electrically conducting, the effect is the same because the cylinder is metallic and the non-conducting plate is not an insulator so far as the lines of force are concerned.

It will be noted that the mounting of the housings 25 on pipe 14 permits their adjustment independently of one another so as to vary the distance of each shell 40 from wire 50 and thereby vary the electrical field surrounding the wire, thus increasing or decreasing the amount of moisture deposited on the plate in the area enclosed by each housing. In this manner a means is provided for controlling the amount of moisture applied at various points transversely of the plate cylinder. The location of pipe 14 is such, in relation to wire 50, throat 36, and the center of cylinder 10, that the adjustments of the housings 2.5 may be made without substantially changing the width of throat 36.

It is also to be noted that the mounting of wire 50 on pipe 14 permits the adjustment of the wire toward and away from the cylinder without changing housings 25, thereby enabling adjustment of the electrical field between the wire and plate.

Having thus described my invention, I claim:

1. In a planographic printing press, the combination with a normally rotating cylinder to be dampened, an electrode parallel to but spaced from said cylinder, an electrically conducting shell enclosing said electrode and open toward said cylinder, means for connecting said electrode to a high potential source of electricity and for connecting said cylinder and said shell to ground to establish a field of force between the electrode on the one hand and the cylinder and shell on the other hand, said shell extending to a point displaced from the electrode in the direction of rotation of the cylinderand closer to the cylinder at that point than the spacing between the cylinder andthe electrode, and means for creating a fog containing finely divided ink-repellent moisture particles and directing it into said field of force, whereby the moisture particles coming within said field of force are deposited either upon said cylinder or upon said shell.

2. Apparatus as defined in claim 1, comprising a pan for liquid disposed beneath said'shell, and means for draining moisture deposited upon the shell downwardly into said pan, said means for creating fog having its liquid intake below the normal liquid level in said pan.

3. Apparatus as defined in clairri 1, characterized by mately equal to the minimum distance between the electrode and the plate on said cylinder.

4. In apparatus for dampening a planographic printing plate, a rotating cylinder upon which the plate is mounted, a wire electrode parallel to but spaced from said cylinder, a connection to said electrode from a high potential source of electricity, an electrically conducting shell partially enclosing said electrode open toward said cylinder, said cylinder and said shell being grounded, means for creating a fog of finely divided moisture particles, and means for directing said fog into the vicinity of the rapidly moving surface of the cylinder in advance of the plane through the electrode and the axis of the cylinder, said shell closely approaching the cylinder on the oppo? site side of said plane to form a narrow throat between the cylinder and the shell, whereby moisture particlesin said fog are charged before they pass through said plane and those which are not previously deposited on the cylinder or shell are attracted either to said cylinder or said shell as they enter said throat.

5. In apparatus for dampening a planographic printing plate, a rotating cylinder upon which the plate is mounted,

a wire electrode parallel to but spaced from said cylinder, 2). connection to said electrode from a high potential source of electricity, an electrically conducting shell partially enclosing said electrode but open toward said cylin-- der, said cylinder and said shell being grounded, a hous ing of which said shellforms the forward wall, means for forming within said housing a-fog of finely divided moisture particles, means for closing the bottom of said housing and forming a passage through which the fog may travel on its Way into the space between the shell and the surface of the cylinder in advance of theiplane through the electrode and the axis of the cylinder, said shell closely approaching the cylinder on the opposite, side of said plane to form a narrow throat between the cylinder and said shell, whereby moisture particles in said fog are charged by said wire electrode and those which are not previously deposited on the cylinder or shell are attracted either to the cylinder or shell as they enter said throat.

6. In apparatus for dampening a planographic printing plate, a rotating cylinder upon which the plate is mounted, a wire electrode parallel to but spaced. from said cylinder, a connection to said electrode from a high potential source of electricity, an electrically conducting shell partially enclosing said electrode open toward said cylinder, said cylinder and said shell being grounded, a

housing. of which said shell forms the forward wall, saidhousing being open at tthe bottom, a pan for liquid beneath said housing into which the housing extends, means for drawing liquid from said pan and forming within the housing above the level of liquid a fog of finely divided moisture particles, and means for directing said fog over the liquid level into the vicinity of the rapidly moving surface of the cylinder in advance of the plane through the electrode and the axis of the cylinder, said shell closely approaching the cylinder on the opposite side of said plane to form a narrow throat between the cylinder and said shell, whereby moisture particles in said fog are charged before they pass through said plane and those not previously deposited upon the cylinder or shell are attracted either to said cylinder or said shell as they enter said narrow throat.

7,. In a planographic printing press, the combination with a normally rotating cylinder, a planographic printing plate thereon, a a straight wire electrode parallel to but spaced from said cylinder on the up-going side there of, an electrically conducting shell enclosing said electrode but open toward said cylinder, said shell comprising a substantially semicylindrical portion disposed at a distance from said electrode approximately the same as the minimum distance between the electrode and the plate on said cylinder, an upper portion of said shell closely approaching said cylinder leaving a narrow throat therebetween, means for creating a fog containing finely divided moisture particles and for conducting the fog toward the cylinder around the lower end of said shell, and means for connecting said electrode to a source of high potential electricity and grounding said cylinder and shell, whereby any moisture particles entering the field of force of said electrode and not previously deposited will be attracted either to said plate or to said shell as they enter said narrow throat under the impetus of the surface friction from said cylinder.

8. In a planographic printing press having a planegraphic plate on a normally rotating cylinder, an elec trode extending along the length of but spaced from said cylinder, means for inducing a high potential electrical discharge from said electrode toward said cylinder, a housing having a slot-like discharge opening toward said cylinder in the vicinity of said electrode, means for creating a fog containing finely divided moisture particles, said fog creating means comprising two opposed nozzles arranged to discharge fluid toward each other, means for supplying liquid to the fluid stream of one of said nozzles causing a liquid spray from the latter nozzle to be met by'the discharge from the other nozzle and a cloud or fog of moisture particles to be formed, said nozzles being disposed in said housing at a point remote from said discharge opening, whereby the fog is spread lengthwise of said slot-like discharge opening and is conducted into the field of force or" said electrode with reduced velocity as compared with that at the nozzles,

9. In a planographic printing press having a planographic plate on a normally rotating cylinder, a straight win electrode parallel to but spaced from said cylinder on the up-going side thereof, a normally fixed pipe mounted on the press parallel to said cylinder above said electrode, means for connecting said pipe to a source of air under pressure, a housing disposed beneath staid pipe and supported thereby, a spray nozzle. disposed to discharge into said housing, an air nozzle in said housing disposed to discharge against the spray from said spray nozzle, an air conductor from said pipe to said air and spray nozzles, the forward portion of said housing comprising a shell open toward said cylinder and closed elsewhere, said housing being adapted to conduct a fog of finely divided moisture particles resulting from the action of said opposed nozzles around the base of said shell into the space between the shell and the cylinder, means independent of said housing for supporting said electrode from said pipe, said housing and electrode being relatively adjustable about said pipe, means for connecting said electrode to a high potential source of electricity and means for grounding said cylinder.

10. In a planographic printing press having a planeg'raphic plate on a normally rotating cylinder, an elongated electrode parallel to but spaced from said cylinder on the tip-going side thereof, a series of housing arranged side by side supported upon the press to the rear of said electrode, individual spray nozzles each disposed to discharge a liquid spray into a housing near the top thereof, an air nozzle in each housing disposed to discharge against the spray from the corresponding spray nozzle, a compressed air conductor for each of said housings connected to the air and spray nozzles associated therewith, each of said housings affording a path of flow for fog created by the opposed nozzles downwardly and then forwardly into the space between the electrode and said cylinder, means for connecting said electrode to a high potential source of electricity and for connecting said cylinder to ground, and means for controlling the air and liquid entering the nozzles of the individual housings, whereby the degree of dampening for different zones of a plate may be varied to suit varying proportions of image and non-image areas'in said zones.

In a .planographic printing press, the combination with a normally rotating cylinder, 0. planographic printing plane thereon, a straight wire electrode parallel to but spaced from said cylinder, a housing supported on the press to the rear of said electrode, means in said housing for creating a fog of finely divided moisture particles and conducting them into the space between said electrode and said cylinder, insulating slabs carried by the press in which the ends of said electrode are mounted, tubular metallic members between said housing and said slabs enclosing those portions of the electrode which extend beyond the housing, means for connecting said electrode to a high potential source of electricity and for grounding said cylinder and tubular metallic members, whereby moisture in any fog entering said tubular metallic members will be deposited upon the internal walls of those members and will not be condensed on the inner sides of said slabs.

12. In a planographic printing press having a planographic plate on a normally rotating cylinder, a normally fixed pipe mounted on the press parallel to but spaced from said cylinder, a series of housings disposed side by side beneath said pipe and supported thereby, means in each of said housings for creating a fog of finely divided moisture particles, the forward portion of each housing comprising a shell of approximately semicylindrical shape open toward said rotating cylinder, the ends of each shell substantially registering with the ends of the shells on either side thereof, each of said housings being adapted to conduct the fog of moisture particles created therein around the base of the shell into the space between the shell and the rotating cylinder, a straight wire electrode parallel to said rotating cylinder supported at approximately the axes of said semi-cylindrical shells, means for connecting said electrode to a high potential direct current source of electricity and means for grounding said cylinder and shell, each of said housings being independently adjustable about said pipe to vary the position of its shell with respect to said electrode and thereby to modify the strength of the field between the rotating cylinder and that portion of the electrode within the shell.

13. A planographic printing press as defined in claim 12, wherein said housings are disposed adjacent the upgoing side of said rotating cylinder and wherein the upper forward portion of each housing approaches closely the periphery of the cylinder, leaving a small throat therebetween, the location of said pipe being such in relation to said electrode, said throat and the center of said rotating cylinder that the adjustments of the housings may be made without substantially changing the width of said throats.

14. A planographic printing press as defined in claim 13, wherein said housings are disposed adjacent the upgoing side of said rotating cylinder and wherein the upper forward portion of each housing approaches closely the periphery of the cylinder, leaving a small throat therebetween, said pipe being disposed approximately in the same vertical plane as said electrode, whereby an adjustment of the housing toward the cylinder by a given amount will result in greater horizontal movement of the shell toward the electrode than the corresponding reduction of the width of said throat.

15. A planographic printing press as defined in claim 8, wherein said nozzles are disposed at a level above that of said electrode and said slot-like discharge opening is disposed below the level of said electrode.

16. Aplanographic printing press as defined in claim 8, wherein the lower part of said housing contains liquid and said means for supplying liquid to the fluid stream of one of said nozzles comprises a conductor extending downwardly into said liquid.

17. Apparatus as defined in claim 3, wherein said shell is partially cylindrical in contour with its axis substantially coincident with said wire.

18. In apparatus for dampening the surface of an electrically grounded rotating cylinder, means providing electrically charged finely divided moisture particles in an electrical field of force adjacent said surface, said last named means including a high potential source of electricity and an electrode parallel to said surface and connected to said electrical source, said charged particles being impelled by said field toward and onto the surface of the grounded cylinder, and a shell enclosing said electrode and comprising a grounded electrically conducting portion displaced from said electrode in the direction of rotation of the cylinder and approaching the cylinder in closer proximity to the latter than said electrode for collecting moisture particles not attached to said surface.

19. In apparatus for dampening the surface of an electrically grounded rotating cylinder, a wire electrode parallel to but spaced from said cylinder, a high potential source of electricity, an electrical connection between said source and said electrode, a shell partially enclosing said electrode and open toward said cylinder, and means for creating a fog of finely divided moisture particles, said fog being directed into the field of force created between the electrode and the grounded cylinder and being enclosed by said shell, a portion of said shell closely approaching the cylinder at a point in advance of the electrode to form a narrow throat between the cylinder and the shell, at least that portion of the shell approaching the cylinder being electrically conducting and grounded to collect fog particles not deposited on the cylinder as the particles enter the throat.

20. In a printing press having a rotating electrically conductive cylindrical member to be coated with finely divided particles, an electrode parallel to but spaced from said cylindrical member, a shell enclosing said electrode and comprising a grounded electrically conductive collector member displaced from said electrode in the direction of rotation of the cylindrical member and extending adjacent to said cylinder in closer proximity to the latter than said electrode, a high potential source connected between said electrode and ground for establishing an electrical ionizing and precipitating field between said electrode and said cylindrical member and an electric field between said electrode and said electrically grounded collector member, and means for providing finely divided coating particles in said ionizing and precipitating field.

21. Apparatus as defined in claim 1, wherein said shell comprises a plurality of independently movable portions arranged along said electrode and wherein supports for said movable portions are provided permitting adjustment of said movable portions to vary their distances from said electrode and thereby vary the electrical field surrounding the wire.

22. Apparatus as defined in claim 1, comprising insulating slabs carried by the press in which the ends of said electrode are mounted, said slabs being spaced apart a distance greater than the length of said shell, grounded electrically conducting members between said shell and said slabs enclosing those portions of the electrode which extend between the shell and said slabs, whereby any moisture particles entering the regions between said shell and said slabs will be deposited upon the inner walls of said conducting members and will not be deposited on the inner sides of said slabs.

References Cited in the file of this patent UNITED STATES PATENTS 2,224,391 Huebner Dec. 10, 1940 2,264,523 Gustafsson et al Dec. 2, 1941 2,357,809 Carlson Sept. 12, 1944 2,408,144 Huebner Sept. 13, 1946 2,447,664 Pegg Aug. 24, 1948 2,486,877 Ransburg et al. Nov. 1, 1949 2,573,881 Walkup et al Nov. 6, 1951 2,583,375 Hooper Jan. 22, 1952 2,710,589 Brunner June 14, 1955 FOREIGN PATENTS 605,979 Great Britain Aug. 4, 1948 

